Circuits for measuring the width (time duration) of electrical pulses are known. The pulses are typically in the form of a current or voltage waveform. The measurement circuit receives-the waveform and provides a visual display of the width of the received pulse.
Known pulse width measurement circuits, however, suffer from operational drawbacks. First, known pulse width measurement circuits must be reset in a manner so that an incoming pulse "triggers" the measurement circuitry. For example, an oscilloscope must be initialized prior to measuring pulses of different widths. The time during which the circuit is reset reduces the time available for actual pulse width measuring to occur an thus limits the measurement efficiency of the circuit.
In addition, known pulse width measurement circuits are often implemented in transistor-transistor logic (TTL) circuitry. TTL circuitry suffers from a fundamental limitation on its speed of operation which occurs because transistors in the circuit are driven into saturation, resulting in an increased propagation time. Accordingly, electrical pulses of extremely short duration (100 nanoseconds or less) may not be able to be measured by conventional TTL pulse width measurement circuits.
Accordingly it is an object of the present invention to provide an automatic high-speed pulse width measurement circuit which does not require resetting for pulses of different widths and which may accurately measure the width of a pulse of less than 100 nanoseconds.